In PV system DC side design, the DC circuit breaker box and DC isolator switch are two critical devices often mentioned yet easily confused. Both belong to the DC switch product category, both feature IP66 ingress protection, IK10 impact resistance, and fire-retardant properties — but they differ fundamentally in core functionality, protection capability, and application scenarios. Choosing the right product not only affects system safety but also directly impacts operational efficiency and return on investment.